• Journal of the Korean Geophysical Society
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• v.5 no.3
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• pp.165-174
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• 2002

Seismic velocity and attenuation coefficient of the rocks under the broad-band earthquake observatories of the Korea Meteorological Administration have been measured in the laboratory by using very high frequency seismic waves. Estimated P velocities of the rocks range from 3.2 km/s to 5.6 km/s, depending on the rock type, mineral, and weathering, while, the attenuation coefficients vary from 0.06 to 4.3 db/kHz-m. It seems that P velocities is inversely proportional to the attenuation coefficients of the rocks. Average travel-time delays of the broad-band stations seem to be related with the measured P velocities in the laboratory.

• Korean Journal of Environmental Agriculture
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• v.16 no.4
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• pp.365-372
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• 1997

Biochemical characteristics and activities of glutathione-S-transferases(GSTs) and carboxylesterase extracted from soybean and corn plants treated with quizalofop-ethyl were investigated. Km value and Vmax of GSTs extracted from soybean and corn plants were $6.7{\times}10^{-3}M$ nmole/mg/min, 50, 20 nmole/mg/min, respectively. Optimum pH of carboxylesterase from soybean and corn was 7.0. Km value and Vmax of carboxylesterase extracted from soybean and corn plants were $4.2{\times}10^{-4}M$, $2.5{\times}10^{-4}M$ nmole/mg/min, 33, 10 nmole/mg/min, respectively. GSTs and carboxylesterase activity were reduced by quizalofop-ethyl. GSTs and carboxylesterse activity of corn was more reduced than that of soybean. When soybean and corn were treated by 80 ppm of quizalofopethyl. Soybean recovered after 10 days elapsing, but corn withered after 3days elapsing.

• Journal of Energy Engineering
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• v.8 no.1
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• pp.95-100
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• 1999

대우자동차는 1992년 이래로 전기자동차 개발사업을 추진하고 있으며 1996년에는 전기자동차의 Fleet 운영시험을 위해 10대의 씨에로 개조형 전기자동차를 제작하였다. 이 씨에로 전기자동차에는 고성능 연축전지, 교류유도전동기, 탑재형 충전기 및 전동조향배력장치 등이 장착되어 있으며 고등기술연구원에서는 전기자동차의 Fleet 운영시험의 일환으로 시외 일반도로 운행조건에서 전기자동차의 에너지비용을 조사하기 위한 연구를 수행하였다. 두 대의 씨에로 전기자동차를 용인시와 안성군 지역의 일반도로에서 1998년 4월부터 운행하였으며 이 운행시험 결과를 바탕으로 일반도로 주행조건에서 씨에로 전기자동차의 에너지비용과 동급의 가솔린자동차인 씨에로 1.5DOHC A/T 차량의 에너지비용을 계산하였다. 두 대의 전기자동차중 한 대의 연비는 5.7 km/kWh이었으며, 다른 한 대의 연비는 5.8 km/kWh이었다. 이에 비해 가솔린자동차의 연비는 13.7 km/l로 년간 20,000 km를 주행한다고 가정할 때 가솔린자동차의 년간 주행비용은 전기자동차의 3.4∼18.0배가 되는 것으로 나타났다. 이 시험을 통해 향후 전기자동차의 개발을 위해 유용하고 가치있는 많은 데이터를 얻었다.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.5
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• pp.509-517
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• 2009

Seagrass meadows are important biogenic habitats for a wide variety of marine animals and plants, a source of organic carbon for commercially important animals, and act as a nutrient filter in estuarine and coastal ecosystems. As such, mapping the distribution of seagrass beds provides us with an important component of management and conservation strategies. To survey seagrass distribution within Deukryang Bay, we directly observed seagrass beds using SCUBA in Boseong-gun, Goheung-gun, and Jangheung-gun. Seagrass distribution in Geogeum and Gumdang islands were not observed. Specifically, we monitored the distribution area, species composition, morphology, density, and biomass of seagrass meadows. Seagarss beds were mapped for Daikum-ri coast, Deukryang island, Yongjeong-ri coast, Samsan-ri coast and Ongam-ri coast. Total seagrass coverage in Deukryang Bay was $5.1\;km^2$, $4.8\;km^2$ of which was Zostera marina, $0.3\;km^2$ Z. caulescence and $0.01\;km^2$ Z. japonica. Z. japonica was found in intertidal zones, Z. marina was found from the intertidal to subtidal zones of 2 m MSL (mean sea level) depth, and Z. caulescence was found in subtidal zones of 2.5-5 m MSL.

• Journal of the Earthquake Engineering Society of Korea
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• v.21 no.1
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• pp.31-39
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• 2017

In this study, to estimate the combination of earthquake magnitude ($M_w$) and distance (R) corresponding to the design spectrum defined in Korean Building Code (KBC) 2016, the response spectra predicted from the attenuation relationships with the variation of $M_w$ (5.0~7.0) and R (10~30km) are compared with the design spectrum in KBC 2016. Four attenuation relationships, which were developed based on local site characteristics and seismological parameters in Southern Korea and Eastern North America (ENA), are used. As a result, the scenario ground motions represented by the combinations of $M_w$ and R corresponding to the design spectrum for Seoul defined in KBC 2016 are estimated as (1) when R =10 km, $M_w=6.2{\sim}6.7$; (2) when R = 15 km, $M_w=6.5{\sim}6.9$; and (3) when R = 20 km, $M_w=6.7{\sim}7.1$.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.2
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• pp.26-38
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• 1994

We demonstrate a repeatless transmission of 2.5 Gbps digital signal over 98 km opticla filbers using optical transmitter and optcial receiver which are designed and implemented using commercially available devices. The optical transmitter is realized by using a distributed feedback(DFB) laser. Temperature of the laser is thermoelectrically stabilized and the output optical power is also stabilized by using negative feedback. The output power of the transmitter is 0 dBm. The optical receiver consists of an InGaAs avalanche photodiode, a preamplifier. an automatic gain control amplifier, and a clock/data regenerator. We find an optimum decision threshold that gives the best receiver sensitivity form the measured V curve. The best sensitivity is -35.5dBm( BER-1*10S010T, PRBS=2S023T -1 ) and the overload power is -9 dBm. Finally, we achieve error free optical transmission with 98 km optical fibers. The exinction ration penalty of 2 dB. the chromatic dispersion penalty of 1 dB, and the total power penalty of 3.0 dB are measured. These results satisfy CCITT recommendation.

• International Journal of Highway Engineering
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• v.18 no.2
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• pp.83-90
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• 2016

PURPOSES : Nowadays, cavity phenomena occur increasingly in pavement layers of downtown areas. This leads to an increment in the number of potholes, sinkholes, and other failure on the road. A loss of earth and sand from the pavement plays a key role in the occurrence of cavities, and, hence, a structural-performance evaluation of the pavement is essential. METHODS: The structural performance was evaluated via finite-element analysis using KPRP and KICTPAVE. KPRP was developed in order to formulate a Korean pavement design guide, which is based on a mechanical-empirical pavement design guide (M-EPDG). RESULTS: Installation of the anti-freezing layer yielded a fatigue crack, permanent deformation, and international roughness index (IRI) of 13%, 0.7 cm, and 3.0 m/km, respectively, as determined from the performance analysis conducted via KPRP. These values satisfy the design standards (fatigue crack: 20%, permanent deformation: 1.3 cm, IRI: 3.5 m/km). The results of FEM, using KICTPAVE, are shown in Figures 8~12 and Tables 3~5. CONCLUSIONS: The results of the performance analysis (conducted via KPRP) satisfy the design standards, even if the thickness of the anti-freezing layer is not considered. The corresponding values (i.e., 13%, 0.7 cm, and 3.0 m/km) are obtained for all conditions under which this layer is applied. Furthermore, the stress and strain on the interlayer between the sub-grade and the anti-freezing layer decrease gradually with increasing thickness of the anti-freezing layer. In contrast, the strain on the interlayer between the sub-base and the anti-freezing layer increases gradually with this increase in thickness.

• Journal of the Earthquake Engineering Society of Korea
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• v.19 no.5
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• pp.247-256
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• 2015

This paper briefly introduces the design seismic loads in Korea (KBC 2009). Then, over 10,000 recorded earthquake ground accelerograms, with their magnitude ranging from 4.0 to 8.0 and their epicentral distance ranging from 0 to 200 km, were used to examine the appropriateness of seismic load defined in Korea known as a low-to-moderate seismicity region. The following conclusions are drawn based on the results: (1) The effective peak ground accelerations (EPA) of recorded earthquake accelerograms under $M{\leq}6.0$ and $R{\geq}15km$ appear to be less than that of MCE in Korea for all site conditions defined in KBC 2009. (2) The design spectrum (two-thirds of the intensity of MCE) in KBC 2009 is comparable to those of earthquake records in the magnitude 6 - 7 and the epicentral distance less than 50 km. Therefore, (3) the intensity of Korean design earthquake is considered to be overly high since the Korea peninsula is generally conceived to be a low-seismicity region.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.3
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• pp.222-228
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• 2013

In this paper, we analyze the optimum moving speed of taxi for maximum revenue. In the analysis, we assume that passengers are distributed exponentially along with the direction as taxi moves. When the taxi arrives at the location of a passenger within the predetermined time limit, the passenger gets in the taxi. Otherwise, we assume that the passenger leaves the location and the taxi does not meet the passenger. We vary taxi speed from 0km/h through 80km/h to see how revenue of a taxi varies, applying the average gas mileage of LPG taxis in Korea. From the results of the analysis, we see that the probability that a taxi meets passengers goes high as taxi speed gets fast, however the revenue starts to fall after the maximum point of revenue at the optimum speed, since fuel cost gets dominant.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.157-161
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• 2011

낙동강하구둑 접근수로에는 상류로부터 유입되는 유사가 유속감소로 인해 하구둑 근처에서 퇴적되는 문제가 발생하고 있다. 퇴적되는 유사를 저감시키기 위한 방법으로 하구둑 건설이후 매년 일정한 통수능 확보를 위해 준설이 수행되어 왔다. 그러나 준설 방법은 많은 비용과 시간이 소모된다는 점에서 효율적이지 못하며, 이를 대체 할 수 있는 적절한 퇴사저감방안 연구가 지금까지 선행연구들을 통해 제안되고 있는 실정이다. 특히 하폭이 급격히 확대되어 유속 감소를 유발하고 유사 퇴적을 야기 시키는 하구둑 상류 2km에서 3km 지점의 하폭을 국부적으로 축소함으로써 효과적으로 퇴사를 저감시킬 수 있을 것으로 나타났다. 그러나 하폭축소로 인하여 홍수발생시 상류의 홍수위가 기존 조건에서 보다 상승할 수 있는 위험성이 있다. 따라서 본 연구에서는 하폭축소 방법으로 인해 발생할 수 있는 상류의 홍수위 상승 위험성을 1차원 수치모형인 HEC-RAS 모형을 이용하여 하폭축소 전 후의 수면곡선을 분석하고자 한다. 연구대상 영역은 낙동강하구둑 상류 12km 구포대교 지점까지이며 하폭축소 구간은 낙동강하구둑 상류 2km에서 3km로 하도 우안 구간의 하폭을 10% 축소하였다. 입력 자료는 낙동강유역 종합치수계획에 명시된 빈도별 유량 및 낙동강하구둑 수위 조건을 적용하였다. 모의결과 30년, 50년, 80년, 200년 빈도별 유량과 수위를 적용한 경우 최대 수위상승이 0.02m이하인 것으로 나타났으며, 500년 빈도의 경우 0.03m의 최대 수위상승 값을 확인할 수 있었다.